add comment to describe what bin/compile does now
add comment to describe what bin/compile does now

jumptvs/BP_Ruby,mattmanning/heroku-buildpack-ruby-jekyll,ericboehs/heroku-buildpack-ruby,andycroll/heroku-buildpack-jekyll,ekaranto/rails4-bluemix-buildpack,brightbytes/heroku-buildpack-ruby-without-assets-precompile,orenyk/heroku-buildpack-ruby,donnykurnia/heroku-buildpack-ruby,ericboehs/heroku-buildpack-ruby,ekaranto/rails4-bluemix-buildpack,ekaranto/rails4-bluemix-buildpack,makifund/heroku-buildpack-ruby,zunda/heroku-buildpack-ruby,brightbytes/heroku-buildpack-ruby-without-assets-precompile,moneyadviceservice/heroku-buildpack-ruby-bowndler,donnykurnia/heroku-buildpack-ruby,ruby/heroku-buildpack-www-ruby-lang,cloudfoundry/ruby-buildpack,instacart/heroku-buildpack-ruby,pilotcreative/heroku-buildpack-ruby,andycroll/heroku-buildpack-jekyll,jumptvs/BP_Ruby,Scalingo/ruby-buildpack,moneyadviceservice/heroku-buildpack-ruby-bowndler,tpope/heroku-buildpack-ruby-tpope,Genius/heroku-buildpack-ruby,jonseaberg/heroku-buildpack-turbo-sprockets,cloudfoundry/ruby-buildpack,heroku/heroku-buildpack-ruby,qnyp/heroku-buildpack-ruby-bower,ekaranto/rails4-bluemix-buildpack,makifund/heroku-buildpack-ruby,pkgr/heroku-buildpack-ruby,instacart/heroku-buildpack-ruby,zunda/heroku-buildpack-ruby,heroku/heroku-buildpack-ruby,pkgr/heroku-buildpack-ruby,qnyp/heroku-buildpack-ruby-bower,mattmanning/heroku-buildpack-ruby-jekyll,jumptvs/BP_Ruby,orenyk/heroku-buildpack-ruby,jonseaberg/heroku-buildpack-turbo-sprockets,cloudfoundry/ruby-buildpack,pilotcreative/heroku-buildpack-ruby,cloudfoundry/ruby-buildpack,tpope/heroku-buildpack-ruby-tpope,cloudfoundry/ruby-buildpack,Genius/heroku-buildpack-ruby,Scalingo/ruby-buildpack,jumptvs/BP_Ruby